Flipping-type graft fixation device and method with low flipping distance

ABSTRACT

A graft retention device has an elongated body with a first and second ends and a midpoint therebetween. A pair of elongated slots formed through the body defines a tang therebetween. A graft retention loop is disposed over the tang and is slidable therealong. A trailing line connects to the body adjacent the slots and extends therefrom through the graft retention loop toward the first end. Tension applied to the trailing line thus tends to urge the graft retention loop away from the first end and toward the midpoint.

BACKGROUND

This application relates to graft fixation, and more particularly tograft tissue fixation employing flipping-type fixation devices.

Flipping-type fixation devices, such as disclosed in U.S. Pat. Nos.5,306,301 and 5,645,588 which are incorporated herein by reference,allow a simple procedure to be used for fixing tissue such as in anAnterior Cruciate Ligament (ACL) reconstruction. Such device comprisesan elongated bar having a central suture loop depending therefrom. Atunnel is prepared in the femur from a position at or near the patellarsurface up through a portion of the femur and exiting through the sideof the femur at a superior location. A graft is looped over the loopattached to the elongated bar. The bar is able to pass in one directionup through the tunnel. After exiting the superior end of the tunnel, thebar is flipped approximately 90 degrees so that it will not pass backthrough the tunnel and is positioned against the femur with the loop andgraft hanging down into the tunnel therefrom. Tension on the graft keepsthe bar in place against the bone surface.

To initiate the flipping, however, the bar must be passed completelyoutside of the tunnel. When it is then placed down against the bone thesuture loop falls back into the tunnel by the amount that it was pulledfree of the tunnel, about 50% of the length of the bar. This decreasesthe contact of the graft with the bone in the tunnel. Also, longer looplengths have the potential to increase motion of the graft within thetunnel, thus potentially slowing the healing process in which the graftattaches to the bone.

U.S. Patent Publication No. 20130204366, incorporated herein byreference, provides a bar in which the graft retention loop is able tomove axially along the bar thereby reducing the distance the graft ispulled out of the tunnel during the flipping procedure.

SUMMARY OF THE INVENTION

A graft retention device according to the present invention comprises anelongated body having a first end and a second end, a midpointtherebetween, and an upper surface and a lower surface. A pair ofelongated slots formed through the body from the upper surface to thelower surface defines a tang therebetween. A graft retention loop isdisposed over the tang and is slidable therealong from a first positioncloser to the first end and a second position closer to the midpoint. Atrailing line connects to the body adjacent the slots and extendstherefrom. When the graft retention loop is in the first position, thetrailing line extends from the body through the graft retention looptoward the first end such that tension applied to the trailing line willthus tend to urge the graft retention loop away from the first positionand toward the second position.

Preferably, the trailing line is attached to the tang, more preferablyby passing through a first aperture through the tang. The first aperturecan be elongated longitudinally along the tang so as to comprise a slottherethrough whereby tension applied to the trailing line forreorienting the body will tend to urge the trailing line toward themidpoint and further enhance its urging of the graft retention looptoward the second position.

Preferably, a leading line connects to the body at the second end.

Preferably, the tang slopes downwardly away from the first end.

Preferably, the graft retention device is provided in a sterilecondition.

Preferably, the second position is located near a midpoint of the bodyand more preferably within a central 25% of a length of the elongatedbody between its first end and its second end.

In one aspect of the invention, the elongated slots are closed at thefirst end via a retention line passing through the tang and attached tothe body. Preferably, the retention line extends beyond the first end ofthe body when the graft retention loop is in the first position wherebyto minimize a flipping distance of the graft retention device.

A method according to the present invention provides for fixing a graftligament into a bone tunnel. The method comprises the steps of: a)forming a graft construct by disposing the graft ligament over a loopslidably disposed upon a tang of an elongated fixation buckle, the loopbeing slidable along the tang from a first position nearer a first endof the buckle to a second position nearer a midpoint of the buckle; b)pulling the graft construct up through the bone tunnel with a second endof the buckle leading; c) after the buckle has been pulled through thetunnel, applying tension to a trailing line connected to the body andpassing through the loop and away from the second position, the tensionurging the loop toward the second position and also reorienting thebuckle to be crosswise to the tunnel on the bone adjacent the tunnelwith the loop depending into the tunnel from the second position on thebuckle.

Preferably, the trailing line is connected to the body at the tang suchas by being received through a trailing line aperture through the tang.Preferably, the trailing line is removed after step c). Preferably, stepb) is performed via a leading line received through a leading lineaperture at the second end of the buckle. Preferably, at least a portionof the loop above an upper surface of the buckle extends beyond thefirst end of the buckle when the loop is in its first position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a fixation device buckle according tothe present invention;

FIG. 2 is a sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a side elevation view in cross-section of a ACL repair in aknee employing the fixation device of FIG. 1;

FIGS. 4A to 4D are side elevation views in cross-section of an ACLrepair procedure employing the fixation device of FIG. 1; and

FIG. 5 is a top perspective view of an alternative embodiment of abuckle according to the present invention.

DETAILED DESCRIPTION

FIGS. 1 and 2 show a graft fixation device 10 according to the presentinvention. It comprises an elongated bar or buckle 12 having a graftreceiving loop 14 depending therefrom. The buckle 12 comprises a firstend 16 and second end 18, and an upper surface 20 and lower surface 22.The terms “upper” and “lower” and related terms such as “upwards” areused herein with reference to the surfaces of the buckle 12 justdefined, with the lower surface 22 being that surface which will face abone (not shown in FIG. 1) when the buckle 12 is employed.)

A pair of longitudinal slots 32 penetrates the buckle 12 from the uppersurface 20 to the lower surface 22 and extends from a first end 34adjacent the buckle first end 16 to a second end 36 at a midpoint 38 ofthe buckle 12. The slots 32 define a retention tang 40 therebetween. Anupper surface 42 of the retention tang slopes downwardly from the firstend 34 of the slots 32 to the second end 36 to encourage the loop 14 tomigrate toward the midpoint 38 at implantation. The loop 14 is receivedthrough the slots 32 and slides along the retention tang upper surface42.

A first hole 24 penetrates the tang 40 laterally adjacent the first end16 and a second hole 26 penetrates the buckle 12 at the second end 18,passing from the upper surface 20 to the lower surface 22. The firsthole 24 receives a trailing line 28 and the second hole 26 a leadingline 30 for guiding the buckle 12 during implantation. As best seen inFIG. 2, when the loop 14 is toward the first end 34 it overlaps thefirst hole 24. When the trailing line 28 is tightened upwardly duringthe flipping portion of implantation it will tend to push the loop 14away from the first end 34. Placement of the hole 24 inboard of thefirst end 34 also allows the first end 34 of the slots 32 to be closerto the first end 16 of the buckle 12 and thereby reduce the flippingdistance.

The trailing line 28 and leading line 30 are preferably formed ofORTHOCORD #2 suture available from Ethicon, Inc. of Somerville, N.J. Theleading line 30 may experience higher stress than the trailing line 28while placing the fixation device 10 as will become apparent as theplacement procedure is described. The second hole 26 is shown slightlylarger than the first hole 24 (although they could be made the samesize) and the leading line 30 can be a higher strength suture such aswith a larger diameter than the trailing line 28. This difference can beused to differentiate the leading line 30 and trailing line 28. They canalso be differentiated in some other fashion such as via varying colorsor visual patterns.

Preferably, the vertical dimension of the retention tang 40 remainsconstant from the first end 34 to second end 36 to enhance its strengthand rigidity, with the retention tang 40 thus depending slightly belowthe buckle lower surface 22 at the midpoint 38. The tang 40 is shownwith a slope below the upper surface 20 of 13.6 degrees but could beanywhere from zero to about 45 degrees. It could also vary in slope,such as getting progressively steeper toward the midpoint 38 toencourage the loop to stay at the midpoint 38 after implantation.

Preferably, for an ACL repair the buckle 12 is approximately 12 mm long,4 mm wide and 1.5 to 2.5 mm thick, with the thickest portion being themidpoint 38 where the tang 40 depends. The tang 40 is approximately 1.5mm thick. The buckle 12 is preferably formed of a biocompatible materialsuch as 6A1-4V Ti alloy. Preferably, the loop 14 is woven of ultra-highmolecular weight polyethylene, such as DYNEEMA, and polyester. Thematerial of the loop 14 is preferably about 2 mm in diameter, preferablybeing in a range of from #2-0 up through about 4 mm, and the loop 14 ispreferably between about 8 mm and 60 mm long. The loop 14 can be wovenonto the buckle 12 to form a continuous loop without knots. U.S. Pat.No. 6,352,603 to Bryant, incorporated herein by reference, illustratesone method for achieving such a construct.

Turning also now to FIG. 3, a graft construct 44 comprises a tissuegraft 46 looped over the loop 14 of the fixation device 10 and is showin place in a patient's leg 48. A tunnel 50 in the leg's femur 52comprises a larger diameter inferior portion or socket 54 sized toaccommodate the graft 46 and a smaller diameter superior portion orpassing channel 56 sized to accept the buckle 12 in a lengthwiseorientation. The buckle 12 sits against the femur 52 in a sidewaysorientation with the loop 14 depending down through the passing channel56 and into the socket 54 in which is placed the graft 46. An oppositeend of the graft 46 is placed into a tibial tunnel 58 in the leg's tibia60 and held in place with an anchor 62 such as the INTRAFIX® anchoravailable from DePuy Mitek Inc. of Raynham, Mass.

Turning also now to FIGS. 4A to 4D the process of passing the buckle 12up through the tunnel 50 and especially the passing channel 56 will bedescribed. At the start of the procedure, the graft tissue 46 isthreaded through the loop 14. A longitudinal axis 60 of the buckle 12 isoriented coaxially with a longitudinal axis 62 of the tunnel 50, withthe loop 14 depending from the first end 34 of the slots 32 (FIG. 4A).Tension on the leading line 30 pulls the second end 18 of the buckle 12upwardly out of the passing channel 56 until the first end 16 is free ofthe passing channel 56 (FIG. 4B). Preferably, the loop 14 and thepassing channel 56 are dimensioned so that if the graft construct 44 ispulled up until the graft tissue 46 abuts an end 55 of the socket 54 thefirst end 16 of the buckle 12 has just cleared the end of the passingchannel 56 thus providing tactile feedback to the surgeon that thebuckle 12 is properly positioned to be rotated. The graft 46 shown inFIGS. 4A to 4D is not to scale and is shown as a thin line so as tobetter illustrate the construction of the socket 54. In reality thegraft 46 would be fatter such that it entirely fills the width of thesocket 54. Contact between the graft 46 and the bone forming the socket54 allows the graft to grow into and merge with the bone to form apermanent repair.

Rotation is approximately 90 degrees and can occur by applying tensionto the trailing line 28 (FIG. 4C). The final orientation depends uponthe angle at which the tunnel 50 penetrates the femur 52. As the buckle12 is rotated, opposing tension supplied by the graft tissue 46 tends tocause the loop 14 to slide along the retention tang 40 leaving itdepending down into the passing channel 56 from the midpoint 38 of thebuckle 12. This occurs with a distinct snapping motion that can be feltby the surgeon through the trailing line 28 to provide tactile feedbackthat the migration has occurred properly. The trailing line 28 andleading line 30 are then removed and tension from the graft tissue 46pulls the buckle 12 lower surface 22 firmly against the femur 52 (FIG.4D). The crosswise orientation of the buckle 12 versus the passingchannel 56 and the loop 14 depending from the midpoint 38 of the buckle12 prevent the buckle from migrating back into the passing channel 56thus providing secure fixation of the graft tissue 46.

The slope of the tang upper surface 42 assists in urging the loop 14toward the midpoint 38. Its angle on the femur 52 versus the tunnel 50also tends to pull the loop 14 across the buckle 12 to sit at the slotsecond ends 36 and the buckle 12. Locating the ends 36 at the midpoint38 thus helps keep the loop 14 seated at the midpoint 38. In terms offinal seating of the loop 14 the term “midpoint” can be broadlyconstrued. Seating at the exact middle of the buckle 12 provides anequal amount of buckle to each side thereof to minimize any chance thatthe buckle 12 can slip along the bone in such a fashion that and endthereof could fall back into the passing channel 56. In practical termsthe loop 14 can be seated in other locations yet still be safelysituated to prevent the buckle 12 from falling back into the passingchannel 56. Preferably, the loop 14 is seated somewhere in the middle50% of the length of the buckle 12 and more preferably within the middle25%.

The flipping distance is representative of the gap between the graft 46and the end of the socket 54. Ideally this gap is zero and the graft 46extends all the way to the end of the socket 54.

FIG. 5 illustrates a further embodiment of a buckle 100 according to thepresent invention. It comprises a body 102 having first and second ends104 and 106 with holes 108 and 110 for trailing and leading lines 107and 109 respectively. It also has slots 112 forming a tang 114 forsupporting a graft support loop 115. The slots 112 extend from amidpoint 116 to the first end 104 rather than being enclosed by the body102 at the first end 104 as in the previous embodiment. To retain theloop on the tang 114 a retaining line 118 is provided through aperture120 in the tang 114 and adjacent apertures 122 in the body 102.

The retaining line 118 can be a suture, wire or other material withsufficient tensile strength to retain the loop. It can be flexible,stretchable or rigid. As shown in FIG. 5 it bows outwardly 124 betweenthe tang 114 and adjacent body 102 to further minimize the flippingdistance, but it could be made straight with no bowing. The bowing 124can be present in a resting state such as being formed in a wire, or mayby dynamically formed under force of the loop 115 against the retainingline 118 if the line 118 is formed of an elastic material whichstretches to form the bowing 124. For instance the line 118 could beformed of a suture with a lower than average modulus of elasticity suchas PDS (Polydioxanone) or Prolene and multiple lengths of such suturecould be employed to form the line 118 with sufficient strength. Rubberor silicone materials, as for instance silicone tubing, of animplantable grade could are other possibilities for an elastic material.The bowing 124 could be formed by the line 118 being flexible, such as asuture, with sufficient slack as to form the bowing 124 especially whenthe loop presses against it.

Fixation of the line 118 in the apertures 122 can be effected byproviding knots 126 the ends of the line 118, particularly if it isformed of suture, such that the knots 126 cannot pass through theapertures 122. Other methods for fixation include welding, adhesives,interference screws etc.

With sufficient bowing 124 the buckle 100 could have a flipping distanceof zero or even a negative value allowing the graft to be seated to theend 55 of the graft socket 54 (not shown in FIG. 5). With sufficientbowing 124 and a negative flipping distance, the graft will reach theend 55 of the graft socket 54 as the buckle 100 is flipped. After theflipping is completed and the buckle 100 is seated against the bone theloop 115 would be pulled upwards versus its position during flippingsuch that a tension in the loop 115 would pull the graft into contactwith the end 55 of the socket 54 with a contact force thereagainstthereby maximizing the bone to graft contact area of the completedrepair. In prior devices this bone surface 55 is wasted as they do notallow the graft to contact it sufficient to achieve ingrowth between thegraft and the bone.

The loop 115 is preferably a continuous closed loop. Formation of such astructure through weaving etc. is made more difficult if it must beformed around the tang 114. With the design of FIG. 5 the loop 115 canbe formed alone which is much easier and then slipped onto the tang 114prior to placing the line 118 onto the buckle 100. This simplifiesmanufacturing.

Refinements and variations to the buckle could include slots whichextend to both sides such that the second side mirrors the first, andthe retention tang sloping down from both ends toward the center. Thiswould allow a surgeon to pull the buckle up through the tunnel 50 byeither end. Also, the upper surface of the retention tang could berounded to provide a better surface for the loop 14 to ride over andlessen chafing of the loop 14.

Provision can be made to discourage the loop 14 from moving away fromthe midpoint 38, such as by providing barbs (not shown) along the uppersurface 42 or other areas of the buckle 12 where they may engage theloop 14 as it slides along the slots 32. The tang can have a pronounceddip to capture and retain the loop 14 at the midpoint.

The buckle is particularly suited to ACL repair, but can be useful inother repairs such as for example reattachment of a biceps brachiitendon.

The invention has been described with reference to the preferredembodiments. Obviously, modifications and alterations will occur toothers upon reading and understanding the preceding detaileddescription. It is intended that the invention be construed as includingall such modifications and alterations insofar as they come within thescope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A graft retention device comprising: An elongatedbody having a first end and a second end, a midpoint therebetween, andan upper surface and a lower surface; a pair of elongated slots throughthe body from the upper surface to the lower surface, the slots defininga tang therebetween; a graft retention loop disposed over the tang andslidable therealong from a first position closer to the first end and asecond position closer to the midpoint; and a trailing line connected tothe tang and extending therefrom, when the graft retention loop is inthe first position, through the graft retention loop toward the firstend such that tension applied to the trailing line will thus tend tourge the graft retention loop away from the first position and towardthe second position.
 2. A graft retention device according to claim 1and further comprising a first aperture through the tang, the trailingline being connected to the tang by passing through the first aperture.3. A graft retention device according to claim 2 wherein the firstaperture passes laterally through the tang.
 4. A graft retention deviceaccording to claim 2 wherein the first aperture is elongatedlongitudinally along the tang so as to comprise a slot therethroughwhereby tension applied to the trailing line for reorienting the bodywill tend to urge the trailing line toward the midpoint and furtherenhance its urging of the graft retention loop toward the secondposition.
 5. A graft retention device according to claim 1 and furthercomprising a leading line connected to the body at the second end.
 6. Agraft retention device according to claim 1 wherein the tang slopesdownwardly away from the first end.
 7. A graft retention deviceaccording to claim 1 which is sterile.
 8. A graft retention device ofclaim 1 wherein the second position is located within a central 25% of alength of the elongated body between its first end and its second end.9. A graft retention device according to claim 1 wherein the elongatedslots are closed at the first end via a retention line passing throughthe tang and attached to the body.
 10. A graft retention deviceaccording to claim 7 wherein the retention line extends beyond the firstend of the body when the graft retention loop is in the first positionwhereby to minimize a flipping distance of the graft retention device.